In a small bowl, combine the cubed chicken breast with Greek yogurt, garam masala, turmeric, sea salt, and black pepper, allowing it to marinate for at least 15 minutes.
Heat the ghee in a large skillet over medium heat and sauté the diced onion, grated ginger, and minced garlic until the onion is translucent and fragrant.
Add the marinated chicken to the skillet and cook for 5-7 minutes, stirring occasionally, until the chicken is lightly browned on all sides.
Pour in the tomato puree and stir to combine, then reduce the heat to low and simmer for 10 minutes until the sauce has thickened and the chicken is fully cooked.
Stir in the coconut milk to create a smooth, creamy texture and let it warm through for 1-2 minutes.
Serve the butter chicken over the cooked basmati rice and garnish with freshly chopped cilantro.